jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Assertions.h>
8#include <AK/ByteBuffer.h>
9#include <AK/JsonObject.h>
10#include <AK/JsonValue.h>
11#include <LibCore/ArgsParser.h>
12#include <LibCore/DateTime.h>
13#include <LibCore/File.h>
14#include <LibCore/System.h>
15#include <LibMain/Main.h>
16#include <unistd.h>
17
18ErrorOr<int> serenity_main(Main::Arguments arguments)
19{
20 TRY(Core::System::pledge("stdio wpath cpath"));
21 TRY(Core::System::unveil("/var/run/utmp", "rwc"));
22 TRY(Core::System::unveil(nullptr, nullptr));
23
24 pid_t pid = 0;
25 bool flag_create = false;
26 bool flag_delete = false;
27 StringView tty_name;
28 StringView from;
29
30 Core::ArgsParser args_parser;
31 args_parser.add_option(flag_create, "Create entry", "create", 'c');
32 args_parser.add_option(flag_delete, "Delete entry", "delete", 'd');
33 args_parser.add_option(pid, "PID", "PID", 'p', "PID");
34 args_parser.add_option(from, "From", "from", 'f', "From");
35 args_parser.add_positional_argument(tty_name, "TTY name", "tty");
36 args_parser.parse(arguments);
37
38 if (flag_create && flag_delete) {
39 warnln("-c and -d are mutually exclusive");
40 return 1;
41 }
42
43 dbgln("Updating utmp from UID={} GID={} EGID={} PID={}", getuid(), getgid(), getegid(), pid);
44
45 auto file = TRY(Core::File::open("/var/run/utmp"sv, Core::File::OpenMode::ReadWrite));
46
47 auto file_contents = TRY(file->read_until_eof());
48 auto previous_json = TRY(JsonValue::from_string(file_contents));
49
50 JsonObject json;
51
52 if (!file_contents.is_empty()) {
53 if (!previous_json.is_object()) {
54 dbgln("Error: Could not parse JSON");
55 } else {
56 json = previous_json.as_object();
57 }
58 }
59
60 if (flag_create) {
61 JsonObject entry;
62 entry.set("pid", pid);
63 entry.set("uid", getuid());
64 entry.set("from", from);
65 entry.set("login_at", time(nullptr));
66 json.set(tty_name, move(entry));
67 } else {
68 VERIFY(flag_delete);
69 dbgln("Removing {} from utmp", tty_name);
70 json.remove(tty_name);
71 }
72
73 TRY(file->seek(0, SeekMode::SetPosition));
74 TRY(file->truncate(0));
75 TRY(file->write_until_depleted(json.to_deprecated_string().bytes()));
76
77 return 0;
78}